The present invention relates to a chuck for a tool, especially a drilling tool.
A chuck is disclosed for example in German document DE-OS 3,046,485 in which a signal device is provided and formed as a high frequency transmitting device with a current source, a high frequency transmitter and a switch in a current supply circuit of the high frequency transmitter. The high frequency transmitting device also has, as a part of the signal transmitter an outer antenna ring. With the exception of this antenna ring, all other components of the high frequency transmitting device including the parts which act on the switch are arranged in the interior of the hollow shaft. However, the outer antenna ring as a part of the signal transmitter is located outside and peripherally of the shaft. The arrangement of the components of the signal device, with the exception of the outwardly located parts of the signal transmitter, in the interior of the hollow shaft, has the advantage that they are reliably protected. However, it also possesses some disadvantages. This arrangement in the interior of the hollow shaft leads to a complicated construction, and also in the case of repair the elements in the interior of the shaft are not easily accessible. Also, the outer diameter of the shaft and thereby the outer diameter of the chuck cannot be reduced below a predetermined value due to the parts located in its interior. This is of disadvantage for example when such a chuck must be used in multispindle drilling machines with relatively small spindle distances. Also, the signal device itself has a relatively expensive construction.